A terminal at New York’s JFK Airport had to be evacuated and hundreds of passengers marched back through security screening Saturday, all because one Transport Security Administration (TSA) agent failed to realize his metal detector had been unplugged, sources said.

The stunning error led to hours of delays, two planes called back from the runway and infinite frustration for furious passengers.

“The truth is, this is the failure of the most basic level of diligence,” a law-enforcement source said.

“How can you expect the public to feel confident of the mission of the TSA if they don’t even know if the lights are turned on?”

The chaos at Terminal 7 was caused by screener Alija Abdul Majed, who had manned Lane No. 1 during the morning shift with no idea his metal detector had no juice, sources said.